The document GB 1 315 223 discloses a building set for toy houses, which comprises wall panels with and without openings for windows or doors, and in which the corner areas are configured with a reduced thickness and with a boss arrangement, so that the wall panels may be assembled by means of a coupling element, which is not described in detail. However, the coupling element is shown as a rod-shaped element in FIG. 17.
One of the drawbacks of the building set is that the panels are configured as hollow moulded elements with edges and ribs, and that the corner area is provided with a boss arrangement, whereby the tooling and production costs will be disadvantageously large.
Another drawback of the building set is that the assembly of the panels with the coupling element must be presumed to be a problem to many small children who do not have fully developed motor skills as yet.
The document DE 2203152 discloses a building set for toy houses, which comprises wall and roof panels and a coupling element. The panels are configured with areas of reduced thickness along the edges, to receive the coupling element. The areas are equipped with depressions on both sides. None of the areas of reduced thickness are placed in the corners of the panel. The coupling element is configured as a wheel equipped with grooves which extend radially outwards from the center of the coupling. The grooves are equipped with bosses.
The shape of the coupling and the positions of the areas of reduced thickness means, that building and removal of the panels has to be conducted in a particular order making assembly difficult for children.
The shape of the coupling element is unfavourable with regard to placing the toy house safely on a floor or table and to the appearance of the house.
The document DE 20 2007 005 299 U1 discloses a building set for a toy castle, which comprises wall panels and coupling elements. The wall panels are configured with permanent secured straps of leather along the vertical edges and positioned to cooperate with the straps on the neighbouring panel and with a metal stick. The straps are secured in a recessed area on the edge of the wall panel, but none of the recessed areas are positioned on the corner of the panel. The coupling element functions as a hinge element, and the wall panels may be turned in different directions. The coupling is loose.
U.S. Pat. No. 5,871,384 discloses a block assembly and devices formed thereby. The block assembly comprises plane blocks and joint blocks. The plane blocks are either solid blocks or blocks configured of an upper plate and a lower plate. The solid blocks are configured with a recessed area in the middle of each of the edges to receive a coupling element. The two-plate blocks are configured with a groove in the middle of the edges to receive a coupling element. Neither the recessed area nor the groove is positioned in the corner of the block. The coupling elements are configured such that when connected to a block, the size of the block is increased.